Field of The Invention
This invention relates to a method and apparatus for polishing an article. More particularly, this invention relates to the use of polyethylene filament to polish articles, preferably of molded plastic reinforced with staple fiber blends, which also need to be deflashed/deburred.
The Prior Art
The removal of the thin ridge or area of roughness produced in cutting or shaping metal is known as deburring. Deburring has been accomplished in many ways, e.g. with vibratory tumblers, flap wheels and abrasive-bristle brushes. With the latter, new grit or cutting edges are continuously exposed to provide a clean tool with long life.
When articles are molded from thermosets, thermoplastics, rubber and the like, the initial product often has extra material called "flash" attached along the mold parting line. Flash results from that portion of the charge which flows from or is extruded from the mold cavity during molding, and is undesirable on most final products. The removal of flash, or "deflashing", has been accomplished in many ways, e.g., deflashing manually with razor blades, rotating or shaking with abrasive media to break off the flash, and deflashing cryogenically.
Deflashing has been complicated by the inclusion of some types of reinforcing staple fiber in compounds to be molded. Many compression molded plastic parts reinforced with nylon or polyester staple fibers (as well as with fiber glass) have a very heavy, excess flashing which cannot be removed by automatic deflashing machines due to a tendency of the flash to adhere to the reinforcing polyester fiber. This problem does not exist with 100 percent fiber glass reinforced plastic parts, since the fiber glass is easily broken off with a crude tool, such as a piece of wood rubbed against the flashing.
Research was directed towards the deflashing of an injection molded part reinforced with a fiber glass and polyethylene terephthalate staple fiber blend. Incidental thereto was the discovery of the polishing effect of the polyethylene filament. The filaments and prdduction thereof may be found in U.S. Pat. No. 4,413,110 to Kavesh et al, U.S Pat No. 4,430,383 to Smith et al., U.S. Pat. No. 4,344,908 to Smith et al., U.S. Pat. No. 4,356,138 to Kavesh et al., U.S. Pat. No. 4,403,012 to Harpell et al., U.S. Pat. No. 4,422,993 to Smith et al., U.S. Pat. No. 4,436,689 to Smith et al., U.S. Pat. No. 4,137,394 to Meihuizen et al., all of which are hereby incorporated by reference.